The invention relates to a navigation device having a range indicator for an electric driving mode of a motor vehicle. The invention also includes a corresponding motor vehicle. The navigation device has an evaluation device for determining a maximum range which it is expected it will still be possible to cover in the current driving mode with a quantity of energy for the electric drive which is stored in an energy storage device of the motor vehicle.
A motor vehicle can comprise a hybrid drive system comprising an internal combustion engine and an electric motor or else a purely electric drive system. In the context of a hybrid traction drive, an electric traction drive is to be understood here as meaning that the electric motor generates the entire driving power or at least part of the driving power. A motor vehicle with a hybrid drive or purely electric drive generally has in the electric driving mode a lower range than a motor vehicle which is driven exclusively by an internal combustion engine and fossil fuel. For this reason, it is very important to make the driver aware of the limited range in the electric driving mode so that the driver adapts his driving behavior and either drives in a low-consumption fashion or heads in good time to a charging station for charging the energy accumulator. In order to ensure this, continuous and as far as possible precise displaying of the section of road which is currently still available and can still be covered with the remaining quantity of energy is necessary.
For this purpose it is known also to represent, on a display device of a navigation device on which a roadmap for the route planning is displayed, an edge of that action area which results from a maximum range, such as it is expected it will still be possible to cover on the basis of the remaining quantity of electrical energy. This edge can have a nonuniform profile in order to inform the driver about the maximum range depending on the section of road. For example, consumption on a freeway may be very much less given an even velocity than travel through an urban area in which the motor vehicle must, for example, be regularly stopped at traffic lights and accelerated again. Furthermore, the consumption can, for example, also depend on the topography of the surroundings, the driving style of the driver and the weather conditions.
The, in certain circumstances, nonuniform edge of the action area has to be clearly discernible on the represented roadmap and must, in particular, be clearly differentiated from the other elements of the road traffic network represented on the roadmap, that is to say for example the freeways and country roads. Otherwise, when a driver is fleetingly considering the display device, he may mistake a line which is intended to represent the edge of the action area for a road, for example. The selection of the color of the line and of the type of line must therefore be matched to the graphics data of the displayed roadmap. A graphics data record is in this context understood as being those data items on the basis of which a specific roadmap for a predefined area is represented and which define a specific assignment of colors and/or textures to the different components of the road traffic network (for example freeways, country roads) and to the geographical information (for example wooded area, built-up area). For example, there are graphics data records for roadmaps which are adapted, on the one hand, to daytime driving and, on the other hand, to nighttime driving. Other examples are a traffic map and a map which is based on satellite images and which can be produced, for example, with image data from the Google-Earth® Internet service. Furthermore, a country scene or an area adjoining the roads can also be represented in different colors depending on the zoom level.
In order then to generate on the basis of such graphics data records a display of such a roadmap on which the edge of the action area is also represented, it is necessary, for example, to match the color of the line representing the edge of the action area to the color palette of the graphics data record. If a new graphics data record is used to represent a specific roadmap, the display device for representing the edge of the action area must also correspondingly be adapted to the new graphics data record.